fix: remove redundant free-tier guard from purchaseCredits

The only caller (TopUpCreditsDialogContentLegacy) is already gated by
showTopUpCreditsDialog, making the bottom-layer check unreachable.

Also adds a doc comment to HAS_ACCOUNT_KEY explaining its purpose.

Author: huntcsg

src/composables/auth/useFirebaseAuthActions.ts

@@ -4,7 +4,6 @@ import { ref } from 'vue'
 
 import { useBillingContext } from '@/composables/billing/useBillingContext'
 import { useErrorHandling } from '@/composables/useErrorHandling'
-import { useSubscription } from '@/platform/cloud/subscription/composables/useSubscription'
 import type { ErrorRecoveryStrategy } from '@/composables/useErrorHandling'
 import { t } from '@/i18n'
 import { isCloud } from '@/platform/distribution/types'
@@ -99,16 +98,6 @@ export const useFirebaseAuthActions = () => {
     const { isActiveSubscription } = useBillingContext()
     if (!isActiveSubscription.value) return
 
-    // Defense-in-depth: showTopUpCreditsDialog also gates free-tier users,
-    // but purchaseCredits can be called directly from other entry points.
-    const { isFreeTier } = useSubscription()
-    if (isFreeTier.value) {
-      await useDialogService().showSubscriptionRequiredDialog({
-        reason: 'top_up_blocked'
-      })
-      return
-    }
-
     const response = await authStore.initiateCreditPurchase({
       amount_micros: usdToMicros(amount),
       currency: 'usd'

src/stores/firebaseAuthStore.ts

@@ -31,6 +31,7 @@ import type { AuthHeader } from '@/types/authTypes'
 import type { operations } from '@/types/comfyRegistryTypes'
 import { useFeatureFlags } from '@/composables/useFeatureFlags'
 
+/** Set after first login; used to detect returning users so the sign-in flow can skip the free-tier badge. */
 export const HAS_ACCOUNT_KEY = 'comfy:hasAccount'
 
 type CreditPurchaseResponse =